Method and system for an exercise unit

ABSTRACT

It is provided an exercise unit incorporating a module for exerting torque countering torque exerted by a user. The exercise unit includes a torque sensor and a processor. The torque sensor includes a first arm connected to a first axis rotatable by the user, and a beam load cell connected to the first arm and associated with a second arm. The second arm is connected to a second axis rotationally associated with the module, and is coaxially coupled to the first axis. Exerting torque on the first axis loads the beam load cell, providing a measured load, which the processor uses to provide a measured exerted torque. The processor is embedded within a motor driver, and its method of operation includes acquiring desired exercising parameters, receiving measurements of motion variable and driving the motor accordingly.

CROSS REFERENCE

The current application claims the priority rights of a U.S. provisional application No. 61/311,787 filed Mar. 9, 2010, by the present inventor, and entitled “METHOD AND SYSTEM FOR AN EXERCISE UNIT”.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is in the field of exercise units or machines, and especially deals with torque applying units having a motor to counter the torque applied by the trainer. It also deals with force applying units having a motor to counter the force applied by the trainer

2. Description of Related Art

Exercise machines are used intensively at home and in special gym clubs for workout and fitness. In a popular class of exercise machines, multi-trainer machine for example, the user is exerting torque on handles that counter the exerted torque. In the past, the counter torque has been provided by a weight, but recently motors have been proposed for providing the counter torque. Such motors may be driven by a computerized driver, or motion controller, which enable to provide flexibility in motion direction, and in the exerted counter torque.

Available torque meters are quite expensive and thus it is an objective of the present invention to provide a torque sensor based on a relatively simple and cheap commercially available component. Also, note that in a device rotating several times the design of the torque sensor has to overcome the challenge of transferring signal originating in a rotating element. Wires, for example, may be entangled while being rotated, and thus a torque sensor based on delivering a signal over wires may be prohibited. However, in many exercise machines an arm is rotated back and forth within a single circle rather than completing full circles. Thus, it is possible to use a torque sensor having wires for signal delivery, without caring about the wiring.

Also, the use of a motor and a computerized controller enables a plurality of operating modes, and it is an objective of the current invention to provide novel operating modes.

BRIEF SUMMARY OF THE INVENTION

It is provided according to some embodiments of the present invention, an exercise unit incorporating a module for exerting torque countering torque exerted by a user. The exercise unit includes a torque sensor and a processor. The torque sensor includes a first arm connected to a first axis rotatable by the user, and a beam load cell connected to the first arm and associated with a second arm. The beam load cell has a loading point at a certain distance from the first axis. The second arm is connected to a second axis rotationally associated with the module, and is coaxially coupled to the first axis. Exerting torque on the first axis loads the beam load cell, and a sampled measured load is available.

The processor receives the measured load and calculates an exerted torque in accordance with said measured load and said certain distance.

In some embodiments, the beam load cell is a planar beam load cell shaped as a substantially box having thickness smaller than 15 mm. In some embodiments, the beam load cell connects two parts of the first arm, a first part connected to the first axis, and a second part connected to the second arm.

In some embodiments, the module for exerting counter torque has two motion resisting modes for the respective clockwise and counter-clockwise rotational directions. The module is adapted to automatically switch between the two motion resisting modes upon change of rotational direction by the user.

It is provided according to some embodiments of the present invention, a method for operating an exercise unit incorporating a module for exerting torque countering torque exerted by a user. The method includes providing a torque sensor, sampling a measured load to get the load exerted on a beam load cell, and calculating an exerted torque in accordance with the measured load and the certain distance. The torque sensor includes a first arm, a second arm and a beam load cell. The first arm is connected to a first axis rotatable by the user. The beam load cell is connected to the first arm and is associated with a second arm, which in turn is connected to a second axis rotationally associated with the module, and coaxially coupled to the first axis. Thus, exerting torque on the first axis loads the beam load cell at a loading point located at certain distance from the first axis.

In some embodiments, the method includes the step of using the measured exerted torque in a control loop for exerting torque in accordance with a desired torque. The control loop may have variable gain coefficients, which may be determined in accordance with motion variables like an angle of the first arm relative to an initial rest position, an angular velocity, an angular acceleration, and a deviation between a desired torque and a measured torque.

In some embodiments, the method includes the step of continuously determining a desired torque in accordance with motion variables.

In some embodiments, the method includes the step of exerting torque pulses during exercising.

In some embodiments, the method includes the step of overlaying vibrations on the exerted torque.

It is provided according to some embodiments of the present invention, a method for a driver of a motor installed in an exercise unit for countering trainer actions, namely, exerting a torque countering the torque exerted by the trainer, or exerting a force countering a force exerted by the trainer. The method includes acquiring desired exercising parameters, receiving measurements of motion variables, and driving the motor in accordance with the desired exercising parameters and the measurements of motion variables. The method also includes driving the motor to exert a desired torque in accordance with said desired exercising parameters, and in accordance with parameters like a torque value determined in accordance with at least two measured motion variables, a fed back control torque signal for reducing the deviation of a measured torque from a desired torque, operating parameters for exerting torque pulses during exercising, a fed back control force signal for reducing the deviation of a measured force from a desired force, and operating parameters for overlaying vibrations on the exerted torque. The fed back control torque signal is determined by the measured values of angular position, angular velocity, or angular acceleration. The fed back force control signal is determined by a position value, a velocity value, a force value or an acceleration value;

Exemplary motion variables are an angle of said first arm relative to an initial rest position, an angular velocity, an angular acceleration, the measured torque, and a deviation between a desired torque, a measured torque, a position, a velocity, an acceleration, a measured force, and a deviation between a desired force and a measured force.

In some embodiments, the control signal has variable gain coefficients which are determined in accordance with the motion variables.

In some embodiments, the method includes receiving data related to a user, storing the data and retrieving it.

In some embodiments, the motion in the exercise machine is linear rather than angular. The method includes a step of driving the motor to exert a desired force in accordance with the desired exercising parameters, and in accordance with a fed back control force signal for reducing the deviation of a measured force from a desired force. The fed back control signal is determined by a position value relative to an initial rest position, a velocity value, an acceleration value, or a force value.

Preferably, the method includes a step of driving the motor to exert a desired force in accordance with the desired exercising parameters, and in accordance with operating parameters for exerting force pulses during exercising. Exemplary operating parameters are a motion variable value for triggering a force pulse, an half width at half maximum duration of a force pulse, and a maximal value of a force provided during a force pulse.

Preferably, the method includes a step of driving the motor to exert a desired force in accordance with the desired exercising parameters, and in accordance with operating parameters for overlaying vibrations on the exerted force. Exemplary operating parameters are an amplitude of the overlaid vibrations, a frequency value of the overlaid vibrations, and a duration of an overlaid vibration train.

It is provided according to some embodiments of the present invention, a system for a motor driver or controller driving a motor exerting torque in an exercise unit. The controller is associated with a motor, with a man-machine interface unit and with motion sensors. The system includes a user interface, sensor interface, and a processor. The user interface receives desired exercising parameters from the man-machine interface unit. The sensor interface receives measurements of motion variables from the motion sensors. The processor drives the motor in accordance with the desired exercising parameters and in accordance parameters like a torque value determined in accordance with measured motion variables, a fed back control torque signal for reducing the deviation of a measured torque from a desired torque, operating parameters for exerting one or more torque pulses during exercising, and operating parameters for overlaying vibrations on the exerted torque. The fed back control signal being determined by the measured values of at least two motion variables,

In some embodiments, the operating parameters for exerting torque pulses are a motion variable value for triggering a torque pulse, an half width at half maximum duration of a torque pulse, and a maximal value of a torque provided during a torque pulse.

In some embodiments the operating parameters for overlaying vibrations on the exerted torque are an amplitude of the overlaid vibrations, a frequency value of the overlaid vibrations, and a duration of an overlaid vibration train.

In some embodiments, the system includes a user database for facilitating receiving data related to a user, storing the data, and retrieving the stored data.

Exemplary motion sensors are a load cell, a torque sensor, an angle sensor, a velocity meter and an acceleration meter.

It is provided according to some embodiments, an exercise machine incorporating a module for exerting torque countering torque exerted by a user. The user uses body parts to rotate rotatable elements associated with the module. The exercise machine includes a module supporting structure for supporting the module, the module having several different module positions, and means for changing position of the module from a first position to a second position.

In some embodiments, the machine further includes a body supporting arrangement for supporting a body of the user, the arrangement having two or more body supporting states, and a support structure for fixedly supporting the body supporting arrangement and for fixedly associating the module supporting structure with the body supporting arrangement. A certain module position and a certain body supporting state are selected mutually to enable appropriate exercising.

In some embodiments, the machine includes at a curved track for supporting the module, preferably a slidably curved track, whereas the module is slidably free to move and be fixed along certain length of the track. Preferably, an electric motor drives sliding movement of the module along the track. Preferably, the curved track is circularly shaped and extremely positioned module positions span an arc of at least 150°.

In some embodiments, the rotatable elements are handles grasped by user hands.

In some embodiments, the exercise machine further includes a torque sensor based on a beam load cell.

In some embodiments, the exercise machine includes a fixation mechanism for fixing the module to the module supporting structure at a desired module position.

In some embodiments, exercise machine includes mechanisms to change length of arms connecting the rotatable elements and the module, thereby fitting a certain module position with a certain state of the body supporting arrangement.

In some embodiments, selecting a state of the body supporting arrangement is associated with actions like aligning a slope of a back rest, varying an height of a seat, and aligning a slope of a seat.

It is provided according to some embodiments of the current invention, a method for exercise machine incorporating a module for exerting torque countering torque exerted by a user. The method includes providing an exercise machine including a module supporting structure for supporting the module, the module having several different module positions, and means for changing position of the module from a first position to a second position. The method also includes disposing the module on a first module position, and changing position of the module to a second module position.

In some embodiments, the exercise machine further includes a body supporting arrangement for supporting a body of the user, the arrangement having several body supporting states, and the method further includes the step of posing the body supporting arrangement at a first body supporting state such that the module position and the body supporting state mutually enabling appropriate exercising.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to system organization and method of operation, together with features and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanied drawings in which:

FIG. 1 is a perspective front view of an exemplary exercise unit which incorporates a torque sensor.

FIG. 2 a is a perspective rear view of a torque sensor and a motor and a belt system for exerting counter torque.

FIG. 2 b is a magnified view of the torque sensor attached to two coupled axes.

FIG. 3 a is a schematic drawing of a torque cell connected to two axes and to a motor.

FIG. 3 b depicts a typical planar beam load cell used in the torque sensor.

FIG. 4 illustrates a torque sensor having a beam load cell within an arm.

FIG. 5 is a flow chart of a method for operating an exercise unit.

FIG. 6 a is a block diagram of a motor driver or controller for driving a motor exerting counter torque in an exercise unit.

FIG. 6 b show an exercise unit having a man-machine interface unit and a USB port for inserting a DISK ON KEY™ having a user personal details.

FIG. 7 is a flow chart of a method for countering trainer actions by a motor in an exercise unit.

FIG. 8 a is a typical torque curve of quadriceps and hamstrings at 60°/sec extension motion.

FIG. 8 b is a typical torque curve of quadriceps and hamstrings at 60°/sec flexion motion.

FIG. 9 illustrates typical isometric and isokinetic torque curves at the knee joint for quadriceps of a male person.

FIG. 10 a illustrates a typical isokinetic curve of torque as a function of angle for a constant angular velocity.

FIG. 10 b illustrates a torque as function of angle curve which incorporates application of torque pluses at predetermined angles.

FIG. 10 c illustrates an exemplary angle versus time curve accepted by application of stopping torque pulses at angles of 30° and 60°.

FIG. 11 is a schematic drawing of a multi-user exercise machine showing three positions of the torque module and two states of a body supporting arrangement.

FIG. 12 is a flow chart of a method for a multi position exercise machine.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in terms of specific example embodiments. It is to be understood that the invention is not limited to the example embodiments disclosed. It should also be understood that not every feature of the methods and systems handling the described device is necessary to implement the invention as claimed in any particular one of the appended claims. Various elements and features of devices are described to fully enable the invention. It should also be understood that throughout this disclosure, where a method is shown or described, the steps of the method may be performed in any order or simultaneously, unless it is clear from the context that one step depends on another being performed first.

Before explaining several embodiments of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The systems, methods, and examples provided herein are illustrative only and not intended to be limiting.

In the description and claims of the present application, each of the verbs “comprise”, “include” and “have”, and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements or parts of the subject or subjects of the verb.

A load cell is a transducer used to convert force into electrical signal. For that sake, a mechanical arrangement deforms a gauge (for example, a strain gauge), which in turn converts the deformation into the electrical signals. A beam load cell is a mechanical structure which incorporates a load cell, a metallic box for connecting two parts while sensing a force exerted on one part by the other part, for example. Throughout this disclosure a beam load cell may be shaped in a different way, S-like shape, for example.

The present invention deals with exercise machines or units in which a user or a trainer applies torque on an axis countering a resistance. Of a large variety of exercise units or machines, some are used for hands workout, while other are used for a legs workout, or for other body parts. A exemplary exercise unit 5, shown in FIG. 1, includes a support structure 10 connected to a seat 12, a back rest 14, a motor driver 16 and a frame 15 having a front board 15 a and a rear board 15 b. A motor 18 and an axis 20 are connected to frame 15. A cylindrical base 23 of an arm 22 encircles axis 20 whereas interface 26 enables angular alignment of arm 22 rest position. An handle 24 is attached to arm 22 such that a user sitting on seat 12 holds handle 24 and rotates it countering torque exerted by motor 18 through a pulley system which includes a pulley 30 and a belt 32. Motor driver or controller 16 includes a processor which gets data from a variety of sources as elaborated below and accordingly drives motor 18 to exert certain counter torque.

FIGS. 2 a and 2 b depict parts enclosed between frame boards 15 a and 15 b, including axis 20, a torque sensor 36, a pulley system 40, and motor 18. Torque sensor 36 includes an arm 42 connected to axis 20, a planar beam load cell 44 connected to arm 42 and to an arm in 46. Arm 46 is attached to pulley 30 which slidably surrounds axis rod 20.

In operation, a user rotates axial rod 20 through handle 24, and thus rotates also arm 42, which in turn exerts force on planar beam load cell 44 and thus causing rotation of arm 46 and pulley 30. Belt 32 rolls over pulley 30 and rotates pulley 50 and pulley 52 which are associated by a common belt 54. Pulley 52 is associated with motor 18 through a transmission system (not shown), of a kind known in the art, and thus motor 18 is able to counter the torque exerted by the user. By limiting the motor current, for example, driver 16 is able to control the countering torque.

Motor driver 16 may drive motor 18 to provide countering torque only in one rotational direction or in both clockwise and counter-clockwise directions. Application of both directions is important for workout of agonist-antagonist muscle pairs, in which an antagonist muscle acts in opposition to the specific movement generated by an agonist muscle and is responsible for returning a limb to its initial position. In the case of bi-directional torque application, the switching of motor torque direction may be achieved automatically, based on reading of the torque sensor, for example. Also, different desired torques and torque curves may be used for the two opposing directions.

In repetitive motion, the switching is done in each repetition. Note that the switching may be preferably done gradually over time or by gradual change of an arm length. Gradual switching prevents sudden and uncontrolled movement in an undesired direction, and fits a gradual change in the torque exerted by the user.

In some exercise machines, the motor exerts torque even before it is used by a user. For example, the rotating arms may have stopping limits and the motor may exert torque against the stopping limiters. On the other hand, it is also possible to have a motion segment of the arms, whereas the motor exerts no torque.

The beam load cell has a loading point 58 at a distance d from the first axis. Exerting torque on the first axis loads planar beam load cell 44 by a force F, causing issue of a respective load measurement. It is well known that T=Fd is the exerted torque. Thus, the processor receives the measured load F and calculates the exerted torque in accordance with the measured load F and the distance d. Actually, rather than directly reading F, a certain voltage is measured, which depends on an applied voltage in a resistors bridge sensing the strain on the load beam. As the distance d is constant for a specific exercise machine, the torque sensor may be calibrated once to obtain a proportionality factor relating the torque to the voltage reading of the beam cell.

Note that a beam cell capable of measuring exerted force for both clockwise and counter clockwise motion is preferably used in the torque sensor. Of course, such a bi-directional beam cell is crucial for exercise machine exerting torque both clockwise and counterclockwise.

FIG. 3 a shows an embodiment of the torque sensor whereas arm 42 projects a vertical part 60 to which planar beam load cell 44 is joined. A typical sample of planar beam load cell 44 is shown in FIG. 3 b which presents a Flintec load cell of maximal load of 375 kg (model c3 1279147). Holes 64 are used to fix load cell 44 to part 60, while hole 66 is used to fix a tab 68 to arm 46. The load on tab 68 causes strain on a strain gage embedded within load cell 44, and the respective change of gauge resistance is translated using resistors bridge 70, wires 72 and a probing circuitry to a load signal read by motor driver 16.

Preferably, planar beam load cell is shaped as a substantially box having thickness smaller than 15 mm.

In some embodiments, a non-planar beam load cell 74 described in FIG. 4 connects parts 76 and 78 of a first arm. Part 78 is connected to axial rod 82, while part 76 is connected to a second arm 80 which rotates with axial rod 84, whereas axial rod 82 and axial rod 84 are co-axially coupled.

Before discussing certain methods for an exercise machine, it should also be understood that the steps of the methods may be performed in any order or simultaneously, unless it is clear from the context that one step depends on another being performed first.

Referring now to FIG. 5, a flow chart of a method 180 for operating an exercise unit incorporating a module for exerting torque countering torque exerted by a user is shown. The method includes step 182 of providing a torque sensor 36, step 184 of sampling a measured load to get the load exerted on a beam load cell 44, and a step 186 of calculating an exerted torque in accordance with the measured load and a certain distance. Torque sensor 36 includes a first arm 42, a second arm 46 and a beam load cell 44. First arm 42 is connected to a first axis 20 rotatable by the user. Beam load cell 44 is connected to first arm 42 and is associated with second arm 46, which in turn is connected to a second axis rotationally associated with the module, and coaxially coupled to first axial rod 20. Thus, exerting torque on first axial rod 20 loads the beam load cell 44 at a loading point located at certain distance from the first axis associated with axial rod 20.

In some embodiments, the method includes a step 188 of using the measured exerted torque in a control loop for reducing deviation of the measured exerted torque from a desired torque. The control loop may have variable gain coefficients, which may be determined in step 190 in accordance with motion variables like an angle of the first arm relative to an initial rest position, an angular velocity, an angular acceleration, and a deviation between a desired torque and a measured torque.

In some embodiments, the method includes a step 192 of continuously determining a desired torque in accordance with motion variables.

In some embodiments, the method includes a step 194 of exerting torque pulses during exercising, as elaborated below.

In some embodiments, the method includes a step 196 of overlaying vibrations over the exerted torque during exercising as elaborated below.

Referring now to FIG. 6 a, it is provided a system 200 for a motor driver 210 driving a motor exerting torque in an exercise unit. Driver 210 is associated with a motor 50, with a man-machine interface unit 240 and with motion sensors like a beam load cell 260, a torque sensor 265, an angle sensor 270, a velocity meter 280, an acceleration meter 290, and an encoder 292. The system includes a user interface 230, sensor interface 250, and a processor 220. User interface 230 receives desired exercising parameters from man-machine interface unit 240, and sensor interface 250 receives measurements of motion variables from motion sensors 260, 265, 270, 280, 290 and 292. Processor 220 drives the motor in accordance with the desired exercising parameters and in accordance with the measurements of motion variables. The driving incorporates actions like continuously determining a desired torque in accordance with motion variables, determining variable gain coefficients of a control loop in accordance with motion variables, applying the control loop to exert a desired torque, exerting torque pulses during exercising, and exerting vibration bursts during exercising.

Note that in some embodiments encoder 292 is attached to one of the pulleys and it counts pulleys revolutions. That count is translated to an arm angle using the corresponding transmission ratios, to angular speed by a single time derivative, and to angular acceleration by a double time derivative. The measurements are very accurate because of an involved high transmission ratio, easily getting accuracy of 1/500 of a degree of an arm angle, for example.

Certain motion variables may be calculated from a measured motion variable. For example, angular velocity may be calculated from angular position by time differentiation, which may be conducted by processor 220.

In some embodiments, user interface 230 includes a user database 245 for facilitating receiving parameters of a user, storing the parameters of the user, and retrieving the stored parameters. For example, a registered user may have an identification code like a number or e-mail address, and in registration the registered user may feed the database with relevant personal parameters like gender, age, weight, height, general health status, and exercise plans. Later on, once a registered user conveys the identification code using man-machine interface unit 240, user interface 230 retrieves the data from database 245 and uses it together with measured motion variables to determine a desired torque.

A typical user interface 240 is shown in FIG. 6 b as part of an exercise machine 241. Alternatively, user interface 240 may be a separate module communicating with driver 241 by a wire or wirelessly. User interface 240 includes a touch screen which enables full bi-directional interaction between a user and exercise unit 241. It may also include its own CPU (central processing unit) or a keyboard.

The user also may use an emergency stop 243 to stop exercise machine 241 in case of emergency. Also, rather than, or in addition to using a database 245 for storing user details, a user may use a personal storage 246 like a DISK-ON-KEY™ device for storing personal details, which the user connects to exercise machine 241 via a USB (universal serial bus) port 244. The exercise machine may store data on an ongoing exercise session on personal storage 246 for retrieval in a succeeding session.

Before presenting method 400 of FIG. 7, it should also be understood that the steps of method 400 may be performed in any order or simultaneously, unless it is clear from the context that one step depends on another being performed first. Also, the steps may be performed several times.

A method 400 for a motor driver driving a torque exerting motor in an exercise unit is depicted in the flow chart of FIG. 7. Method 400 includes a step 402 of receiving parameters of a user, a step 404 of storing the parameters in a database 24, a step 408 of retrieving the stored parameters from database 245, a step 420 of acquiring desired exercising parameters, and a step 430 of receiving measurements of motion variables or calculating them. Method 400 also includes a step 450 of receiving measurements of motion variables, and a step 440 of driving the motor to exert a desired torque in accordance with the desired exercising parameters and the measurements of motion variables.

In some embodiments the method includes a step 450 of determining variable gain coefficients of a control loop in accordance with motion variables, a step 460 of applying the control loop, or several control loops, to exert a desired torque, a step 470 of exerting torque pulses during exercising, and a step 480 of overlaying vibrations on the exerted torque.

With reference to driving a desired torque in accordance with motion variables, FIG. 8 a and FIG. 8 b show typical torque versus angle curves of quadriceps and hamstrings at 60°/sec in respectively extension motion and flexion motion. A torque curve of a muscle presents the torque that the muscle can apply while there is a certain angle between bones connected by the muscle. Thus, FIGS. 8 a and 8 b clearly show that the torque strongly depends on the motion mode, extension or flexion. An exercise unit fits the torque it applies to the torque which may be applied by the appropriate muscle of the user. Usually, the torque exerted by the motor is less than the maximal torque that the user muscles may apply, such that the user is able to move the arms. Therefore, the driver or controller uses data on the muscle motion mode and on the angular motion variable to determine the desired curve.

Note, however, that the desired torque may be determined by more than a single motion variable, as shown in the example of FIG. 9 which depicts typical isometric and isokinetic torque curves at the knee joint for quadriceps of a male person. In isokinetic motion, the angular velocity is kept constant while the applied torque by the user is measured. The curves of torque as function of the angle with angular velocity as a parameter show that the torque is determined by two motion variables, the variable angle and the angular velocity. Thus, the motor driver determines the desired torque continuously in accordance with those two motion variables, whereas in other examples it may use other or additional motion variables.

With reference to action 450 of determining variable gain coefficients of a control loop in accordance with motion variables, note that a control loop reduces a deviation or error between a desired value of a control variable, the torque and the force for example, and the actual value of that control variable. Usually, a term associated to the error is fed back to a driver affecting the control variable such that the error vanishes in a while. More generally, the fed back term may be a sum of three terms, proportional respectively to the error itself, the integral of the error function over certain time window, and the derivative of the error function. In the current document the coefficients of proportionality are called PID gain coefficients, whereas P stands for the error, I stands for the error integral over time and D stands for the error time derivative. Regarding torque applied in an exercise unit, rather than having constant PID gain coefficients, it is provided that the gain coefficients are variable gains depending on measured motion variables, and these variable gain may be changed dynamically in real time. Also, several control loops may be applied simultaneously or consecutively.

Referring now to FIGS. 10 a, 10 b and 10 b, they illustrate two examples of action 470 of exerting torque pulses during exercising. For the sake of comparison, FIG. 10 a shows a typical torque curve provided by an exercise machine. In the example of FIG. 10 b, during exercising the user or trainer arm approaches certain angle wherein the torque rises abruptly to a torque peak value 610, thus imposing an motion obstacle to the user. In response, the user may apply a larger torque and overcome the obstacle, moving forward to a next “stopping point” of a torque peak 620.

Preferably, the half width at half height of torque peak 610 is in the range of 0.1-5°. The torque pulses may be introduced by appropriate pulse programs, and include pulse introduction at coincidental times, a variety of pulse heights, time duration, etc.

Also, torque peaks 610 and 620 may be as high as almost the ability of the trainer, such that the user has to almost stop for a while, after which the torque versus angle curve returns to its normal shape and the user may continue moving, as in isometric training wherein the trainer flexes muscles without motion.

In the example of FIG. 10 c, the exercise unit is in an isokinetic mode of operation wherein the angular velocity is constant at a predetermined value as exemplified by angle versus time curve 630. In a torque pulse mode of angle versus time curve 640, whenever the trainer approaches an angle of 30°, the desired angular velocity is made vanished for a certain period of time, resulting in a plateau 650 in curve 640, designating a stopping is period. Note that such stopping points may be as well introduced in torque curve which is not isokinetic.

Preferably, the stopping period may last in the range of 0.1-20 sec, more preferably 0.1-2 sec, and alternatively 5-20 sec. Note that the 5-20 sec stopping period range is especially appropriate for an isometric training whereas one wants to flex muscles without motion.

The slopes of peaks 610, 620 or plateau 650 may be programmed such as to fit the trainer favorite exercising modes, for example.

With regarding to step 480 of overlaying vibrations on the exerted torque, it is noted that the vibrations may be exerted by motor controller 210 or by an independent device which is coupled directly to arm 22. Such a device may be driven by motor controller 16 or by a separate controller. Any of those controllers or drivers may determine parameters of the overlaid vibrations like frequency, amplitude, duration of a vibration burst, slope of a varying amplitude, and slope of a varying frequency, for example.

A multi-position exercise machine 700 is presented in FIG. 11. It incorporates a module 710 a for exerting torque countering torque exerted by a user. The user sits on seat 720 and uses hands to rotate handles 730 connected by arms 740 to module 710 a. Exercise machine 700 includes a body supporting arrangement 750 for supporting the user body, curved track 755 for supporting module 710 a, and a support structure 760 for fixing exercise machine 700 to a floor, fixedly supporting the body supporting arrangement 750 and fixedly supporting curved track 755. The module has different module positions available on the track, including for example position 710 a at the upper part of curve 755, position 710 c at the lower part of curve 755, and position 710 b in between. Body supporting arrangement 750 has several body supporting states. For example, back rest state 765 a is corresponding to module position 710 a, whereas back rest state 765 c is corresponding to module position 710 c. A fixation mechanism 770 fixes the module to the track at a desired module position 710 a.

In some embodiments, a slidably curved track 755 is used to support module 710 a, and the module is slidably free to move and be fixed to a certain position along certain length of the track. Preferably, an electric mechanism 775 applies sliding movement of module 710 a along track 755. Preferably, curved track 755 is circularly shaped, and extremely positioned module positions 710 a and 710 c span an arc of at about 150°.

In some embodiments, exercise machine 700 includes torque sensor 36 based on a beam load cell 44, as described above.

It is provided according to some embodiments of the current invention, a method 800 for a multi-position exercise machine, as depicted in the flow chart of FIG. 12. The method includes a step 810 of providing an exercise machine 700, a step 820 of disposing module 710 a on a certain module position, and a step 830 of posing body supporting arrangement 750 at a body supporting state such that module position 710 a and body supporting state 765 a mutually enable appropriate exercising. Method 800 also includes step 840 of changing the module position to a second position 710 c, and accordingly pose the body supporting arrangement to state 765 c.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. In particular, the present invention is not limited in any way by the examples described. 

1-38. (canceled)
 39. A high-viscosity, substantially homogeneous paste comprising An exercise unit incorporating a module for exerting torque countering torque exerted by a user, the exercise unit including: (a) a torque sensor comprising: (i) a first arm connected to a first axis rotatable by the user; (ii) a beam load cell associated with said first arm and associated with a second arm, said beam load cell having a loading point at a certain distance from said first axis, and exerting torque on said first axis loading said beam load cell and sampling a measured load; and (iii) said second arm being associated with a second axis rotationally associated with the module, and coaxially coupled to said first axis; and (b) a processor adapted to receive the measured load and calculate an exerted torque in accordance with said measured load and said certain distance.
 40. The exercise unit of claim 39, wherein said beam load cell is a planar beam load cell shaped as a substantially box having thickness smaller than 15 mm.
 41. The exercise unit of claim 39 wherein said beam load cell connects two parts of a certain arm selected from the group consisting of said first arm and said second arm, a first part connected to a respective axis associated with said certain arm, and a second part connected to the other arm of said first arm and with said second arm.
 42. The exercise unit of claim 39, wherein the module is adapted to apply counter torque for both clockwise and counter-clockwise rotational directions, and for automatically switching between the two counter torque directions upon change of rotational direction by the user.
 43. The exercise unit of claim 39 further including: (a) a motor driver driving a motor exerting torque in the exercise unit, the driver being associated with the motor, and with a man-machine interface unit; (b) a user interface adapted for receiving one or more desired exercising parameters from said man-machine interface unit; (c) one or more sensor interfaces adapted for receiving measurements of motion variables from one or more motion sensors; (d) said processor adapted for driving the motor in accordance with said desired exercising parameters and in accordance with at least one parameter selected from the group of parameters consisting of: (i) a torque value determined in accordance with at least two measured motion variables; (ii) a fed back control torque signal for reducing the deviation of a measured torque from a desired torque, the fed back control signal being determined by at least two values selected from a group of values consisting of an angular position relative to an initial angular rest position, an angular velocity, and an angular acceleration; (iii) one or more operating parameters for exerting one or more torque pulses during exercising; and (iv) one or more operating parameters for overlaying vibrations on the exerted torque.
 44. The exercise unit of claim 43, wherein the system further includes a storage for facilitating receiving data related to a user, storing data related to a user, and retrieving data related to a user.
 45. The exercise unit of claim 43, wherein said one or more motion sensors include at least one sensor selected from the group of sensors consisting of, an angle sensor, a velocity meter and an acceleration meter.
 46. A method for operating an exercise unit incorporating a module for exerting torque countering torque exerted by a user, the method comprising: (a) providing a torque sensor comprising: (i) a first arm connected to a first axis rotatable by the user; (ii) a beam load cell associated with said first arm and associated with a second arm, said beam load cell having a loading point at a certain distance from said first axis; and (iii) said second arm being connected to a second axis rotationally associated with the module, and coaxially coupled to said first axis; and upon exerting torque on said first axis loading said beam load cell (b) sampling a load measurement to determine the load exerted on said beam load cell; and (c) calculating a measured exerted torque in accordance with said measured load and with said certain distance.
 47. The method of claim 46 wherein the method further includes the step of using the measured exerted torque in one or more control loops for reducing the deviation of the measured exerted torque from a desired torque.
 48. The method of claim 47 wherein a control signal depends on the measured exerted torque and on at least one additional motion variable.
 49. The method of claim 48 wherein the control signal has at least one variable gain coefficient which is determined, in accordance with at least one motion variable selected from the group of variables consisting of an angle of said first arm relative to an initial rest position, an angular velocity, an angular acceleration, and a deviation between a desired torque and a measured torque.
 50. The method of claim 46 wherein the method further includes the step of continuously determining a desired torque in accordance with at least two motion variables.
 51. The method of claim 46 wherein the method further includes the step of exerting one or more torque pulses during exercising.
 52. The method of claim 46 wherein the method further includes the step of overlaying vibrations on the exerted torque.
 53. The method of claim 46 wherein the exercise unit includes a driver of a motor installed in an exercise unit for countering trainer actions, the method further comprising: (a) acquiring one or more desired exercising parameters; (b) receiving one or more measurements of motion variables; (c) driving the motor to counter trainer actions in accordance with said desired exercising parameters, and in accordance with at least one parameter selected from the group of parameters consisting of: (i) a torque value determined in accordance with at least two measured motion variables; (ii) a fed back control torque signal for reducing the deviation of a measured torque from a desired torque, the fed back control signal being determined by at least two values selected from the group of values consisting of an angular position value relative to an initial angular rest position, an angular velocity value, and an angular acceleration value; (iii) a fed back control force signal for reducing the deviation of a measured force from a desired force, the fed back control signal being determined by at least two values selected from the group of values consisting of a position value, a velocity value, a force value and an acceleration value; (iv) one or more operating parameters for exerting one or more torque pulses during exercising; and (v) one or more operating parameters for overlaying vibrations on the exerted torque.
 54. The method of claim 53 wherein the method includes a step of driving the motor to exert a desired force in accordance with said desired exercising parameters, and in accordance with a fed back control force signal for reducing the deviation of a measured force from a desired force, the fed back control signal being determined by at least two values selected from the group of values consisting of a position value relative to an initial rest position, a velocity value, an acceleration value, and a force value.
 55. The method of claim 53 wherein the motion variables are selected from the group of motion variables consisting of an angular position relative to an initial angular rest position, an angular velocity, an angular acceleration, a deviation between a desired torque and a measured torque, a position, a velocity, an acceleration, a measured force, and a deviation between a desired force and a measured force.
 56. The method of claim 53, wherein the method further includes at least one step of storing said data related to said user, and retrieving data related to said user. 